The present invention relates to a swivelling, sliding closure unit or sliding gate for controlling the discharge of molten metal from a metallurgical vessel. The invention more particularly relates to such a unit of the type including a movable frame or housing carrying a movable or sliding refractory plate and suspended by a universal joint axle on one arm of a dual arm swivel lever operated by a power transmitter or moving device and having as its swivel axis a ball joint which forms another universal joint axle and which is guided, while being resiliently supported on a second arm of the lever, by a raceway and rolling element.
This general type of swivelling, sliding closure unit is disclosed in West German Patent No. 19 28 400 wherein there is shown a movable housing arranged to move on a universal joint and which is capable of adapting the sliding surface of the movable plate to practically any position of the complementary sliding surface of the fixed or stationary bottom refractory plate. During operation of this type of unit, i.e., during relative movement of the complementary sliding surfaces of the two refractory plates, changes in position and deformations, for example, resulting from thermal stresses and high static pressures are compensated. As a result, a uniform compressive load always is exerted on the complementary sliding surfaces. This provides for a reliable seal, particularly since spring mechanisms which operate to press the movable plate toward the stationary plate and are subject to deterioration can be located at safe positions relatively far from the discharging stream of